The susceptibility to contamination during ultra pure processing of sensitive materials such as semiconductors is a significant problem faced by manufacturers. Since the processing of the sensitive materials often involves direct contact with process fluids, it is critical that the process fluids are delivered to the processing site in an uncontaminated state and without foreign particulates. Various manufacturing systems have been designed to reduce the contamination of the sensitive materials by foreign particles and vapors generated during the manufacturing process.
The processing equipment typically includes liquid transporting systems that carry the process fluids, which are often caustic or hazardous, from supply tanks through pumping and regulating stations and through the processing equipment itself. The liquid chemical transport systems include pipes, tubing, monitoring devices, sensing devices, valves, fittings and related devices, and conventionally used metal parts which are susceptive to the corrosive environment when exposed for long periods of time. Hence, the monitoring and sensing devices typically incorporate substitute materials, such as plastics resistant to deteriorating effects of the caustic chemicals, or remain isolated from the caustic fluids.
Semiconductor manufacturing processes may require the discharge of very precise quantities of fluids and commonly use one or more monitoring, valving, and sensing devices in a closed loop feedback relationship to monitor and control this highly sensitive process. These monitoring and sensing devices must also be designed to eliminate any contamination that might be introduced. In order to control the flow or pressure within the fluid transporting system, the transporting equipment may utilize information obtained from each of the monitoring, valving and sensing devices. The accuracy of the information obtained from each of the devices may be affected by thermal changes within the system. Further, the inaccuracy of one device may compound the inaccuracy of one of the other devices that depends upon information from the one device. Further, frequent independent calibration may be required to maintain the accuracy of each individual device. Independent calibration of the devices, however, may prove difficult and time consuming.
These monitoring and sensing devices commonly control the flow or pressure within the fluid transporting system by measuring the differential pressure flow across a constricted area or orifice. Over the passage of time, an orifice invariably erodes or clogs requiring replacement of the entire monitoring and sensing device. Also, it may be desirable to increase or decrease the constricting area of the orifice within the fluid flow circuit to control the flow or pressure of the same or different fluids.
Hence, there is a need for a non-contaminating fluid control module which may be positioned in-line within a fluid flow circuit carrying corrosive materials, wherein the module is capable of determining the rate of flow based upon a pressure differential measurement taken in the fluid flow circuit, and wherein the determination of the rate of flow is not adversely affected by thermal changes within the fluid flow circuit, and wherein calibration of the pressure sensors of the fluid control module does not require ancillary or independent calibration of the valve. A need also exists for a fluid control module that avoids the introduction of particulates, unwanted ions, or vapors into the flow circuit. There is also a need for a fluid control module with a removable or replaceable orifice to eliminate replacement of an entire module or for allowing field selectable calibration of different fluid types or viscosities. Further, there is a need for a reduction in the size and weight of a fluid control module to preserve the often-valuable space in such processing systems. Thus, the embodiments of the present invention are directed to a fluid control module that seeks to overcome these and certain other limitations of the prior art.